Power supply apparatus and electronic device

Abstract

A power supply apparatus includes a DC-DC converter configured to convert an input voltage into an output voltage in accordance with a duty cycle which is decided by a difference of a third signal, a first photo coupler configured to output a first signal corresponding to the output voltage, a converter configured to convert the output voltage into a digital signal, and a second photo coupler configured to output a second signal corresponding to the digital signal, a memory, and a processor coupled to the memory and configured to calculate a third signal on the basis of the difference between the first signal and the second signal, and control the DC-DC converter so that the third signal is to be zero.

What is claimed is: 
     
         1 . A power supply apparatus comprising:
 a DC-DC converter configured to convert an input voltage into an output voltage in accordance with a duty cycle which is decided by a difference of a third signal;   a first photo coupler configured to output a first signal corresponding to the output voltage;   a converter configured to convert the output voltage into a digital signal; and   a second photo coupler configured to output a second signal corresponding to the digital signal;   a memory; and   a processor coupled to the memory and configured to:   calculate a third signal on the basis of the difference between the first signal and the second signal; and   control the DC-DC converter so that the third signal is to be zero.   
     
     
         2 . The power supply apparatus according to  claim 1 ,
 wherein intervals at which the second photo coupler transfers the second signal are longer than intervals at which the first photo coupler transfers the first signal.   
     
     
         3 . The power supply apparatus according to  claim 1 ,
 wherein the rate of outputting the second signal from the second photo coupler is lower than the rate of outputting the first signal from the first photo coupler.   
     
     
         4 . The power supply apparatus according to  claim 1 ,
 wherein a power supply voltage to be supplied to the converter and the second photo coupler or supplied to the converter or the second photo coupler is blocked for a time period for which the second photo coupler does not transfer the second signal.   
     
     
         5 . The power supply apparatus according to  claim 1 ,
 wherein the processor adjusts, based on the difference, the degree at which the first signal is amplified.   
     
     
         6 . The power supply apparatus according to  claim 1 ,
 wherein the processor corrects the first signal output from the first photo coupler, based on the addition of the first signal output from the first photo coupler to the difference.   
     
     
         7 . An electric device comprising:
 a DC-DC converter configured to convert an input voltage into an output voltage in accordance with a duty cycle which is decided by a difference of a third signal;   a first photo coupler configured to output a first signal corresponding to the output voltage;   a converter configured to convert the output voltage into a digital signal; and   a second photo coupler configured to output a second signal corresponding to the digital signal;   a memory;   a processor coupled to the memory and configured to:   calculate a third signal on the basis of the difference between the first signal and the second signal,   control the DC-DC converter so that the third signal is to be zero, and   predict a life of the first photo coupler on the basis of the first signal; and   a display configured to display information of the life.